1. Field of the Invention
The present invention pertains to a digital camera, and more particularly, to a digital camera that performs photo-taking of a two dimensional image by means of a line sensor.
2. Description of the Related Art
A digital camera that performs photo-taking using a combination of a line sensor and a scanning mechanism, such as a mirror rotation mechanism, has been conventionally proposed (Japanese Laid-Open Patent Application No. 62-47278). This type of digital camera is called a line sensor camera. A line sensor camera has the advantage of being able to perform higher-resolution photo-taking than a digital camera that employs an area sensor. For example, photo-taking of an entire A4-sized sheet of paper may be performed such that regular-sized characters on the page may be read.
By incorporating into the line sensor camera a zoom unit as a lens system to perform magnification, the amount of freedom in framing the photo may be increased, improving user convenience.
However, in a line sensor camera having a construction in which the optical axis of the lens system moves relative to the photo object in conjunction with secondary scanning, e.g., in a line sensor camera in which a mirror to perform secondary scanning is located on the front side of the lens system, when the lens system focal length changes during the zooming operation (that is, when the image magnification changes), a problem occurs that the aspect ratio of the object image (photo image) on the image pickup surface of the line sensor also changes.
In view of the situation described above, the object of the present invention is to provide an improved digital camera.
Another object of the present invention is to provide a line sensor camera in which the aspect ratio of the object image on the image pickup surface does not change when the image magnification changes.
These and other objects are achieved by providing a digital camera equipped with the following components:
an image reader which reads an optical image projected thereon and generates image signals by scanning the projected optical image;
an optical unit which projects the optical image on the image reader at various ratios; and
a controller which determines a range of the scanning operation performed by the image reader in accordance with the ratios employed by the optical unit.
The photo-taking range in the direction of main scanning (i.e., the direction of alignment of the image pickup elements of the line sensor) depends on the focal length. On the other hand, the photo-taking range in the direction of secondary scanning depends on the angle of rotation of the scanning mechanism during photo-taking. Therefore, if the angle of rotation in the direction of secondary scanning used for photo-taking is increased or decreased in response to a change in the focal length (i.e., a change in the magnification), the aspect ratio of the object image on the image pickup surface may be made constant.
These and other objects, advantages and features of the invention will become apparent from the following description thereof taken in conjunction with the accompanying drawings which illustrate specific embodiments of the invention.